Can I set my account to exit my position and cancel orders at a certain time of day?

Yes you can set the platform to exit your position and cancel any working orders at a time you specify. 

To do this, expand the Equity and P/L dropdown in the top navigation:

The Configuration Modal will allow you to enable/disable this function and set the time of the current calendar date you would like to flatten:

When it executes, Positions will be exited and working orders will be canceled:

Once executed, the function will be “disabled” so you can enable this for each session you would like.